1. Field of the Invention
This invention relates to the field of communications. More specifically, the invention comprises a method for using an inexpensive VGA cable to connect a variety of different radio devices, along with the hardware used to carry out the method.
2. Description of the Related Art
The present invention has application to a wide variety of communication equipment. However, is it particularly suited to the field of amateur radio. FIG. 1 shows the major components of an amateur radio (excluding the antenna assembly). Radio 10 contains most of the electronics, including the transmitter and receiver. The user controls were traditionally mounted on the same housing. However—in recent years—many units feature a separate control panel which may be mounted on the housing or mounted separately. This separate panel is known as a “control head.”
FIG. 1 shows such a configuration. Control head 12 is separate from radio 10. The control head contains knobs, message displays, input keys, etc. In most units, it contains all the elements a user needs to control the functions of the radio. Thus, the control head and the radio must be connected via a communication cable. Control cable 18 serves this purpose. The illustration shows a typical control cable. Amateur radio manufactures generally use one or more “registered jacks” to connect transmitter/receiver (“transceiver”) units to microphones and remotely located controls. The term “registered jack” (“RJ”) is a consequence of Bell System's requirement to offer competitors access to telephone systems in offices and homes. RJ standard jacks provide a method of interconnecting data or telecommunications devices to service providers. Although technically “RJ” refers to jacks, the term applies currently to both plugs and jacks.
Initially, RJ modular connections were named RJ11, RJ12, RJ21, RJ41, etc. However, they differed only in the number of positions and conductors. The RJ12 jack has six positions and six conductors and is often identified as “6P6C.” The RJ11, which is physically identical to the RJ12, has only four conductors and is identified as 6P4C. Jacks are downward compatible with plugs having fewer positions. Thus, a 6P6C jack physically accommodates 4P4C plugs. However, only the inner 4 conductors of a 6P6C jack are connected to the 4P4C conductors. Similarly, an 8P8C jack accommodates 6P and 4P plugs. Because plugs with fewer positions fit into 8P8C jacks, an RJ jack with eight positions and eight conductors is ideal for interconnecting amateur radio devices that use 4P4C, 6P6C, and 8P8C plugs and jacks.
The de facto standard 8P8C jack is usually referred to as an RJ45, and that is the term this document will use to identify jacks 48 and 50 in FIG. 4. Thus, hereinafter, “RJ45” is defined as an 8P8C registered jack that accommodates registered jacks with fewer positions and/or conductors. Most amateur radio transceivers utilize RJ45 jacks, as defined in this paragraph, to connect microphones and control heads to transceivers.
First female RJ45 jack 24 is provided on radio 10 in FIG. 1. This receives the first male RJ45 plug 32 on control cable 18. The opposite end of control cable 18 terminates in second male RJ45 plug 34. This plugs into second female RJ45 jack 30 on control head 12. Thus, the user may locate control head 12 remotely from radio 10 by linking the two components with control cable 18.
There is no standard in the amateur radio industry for the function or even the number of conductors used in cable 18. Each manufacturer wires its cables independently of other manufacturers and, in fact, varies the wiring of connecting cables within its own product lines. Thus—referring back to FIG. 1—a control cable 18 furnished by one manufacturer to connect its control head to its radio will likely not work for a second manufacturer's radio or even a different radio in its own product line. Manufacturers will use the available pins on the RJ45 for different purposes, and to connect one radio's cables to another radio is not only likely to fail, but may seriously damage the radio.
Microphone cable 20 is likewise not standardized within the industry. It is connected to radio 10 by plugging third male RJ45 plug 36 into third female RJ45 jack 26 on radio 10. This allows microphone 14 to be located a desired distance away from radio 10. However, a microphone cable 20 from one manufacturer will likely not function with components furnished from a different manufacturer.
An example of the lack of standardization is provided by considering the pinouts the microphone RJ45 jacks of two specific radios offered by two prominent manufacturers within the industry—Yaesu and Kenwood. For the Yaesu and Kenwood models, the pin functions are as follows:
Pin NumberYaesuKenwood1GNDNONE2FAST+8 VDC3PTTGND4MICPTT5MIC GNDMIC GND6+5 VMIC 600 Ω7UPNONE8DOWNSERIAL DATA
From these two examples, one may easily perceive how using one manufacturer's cable on another manufacturer's product could cause many problems, including, in this case, destroying both microphones by applying voltages incorrectly.
The only standardized connection typically involves speaker 16, which is connected to radio 10 using speaker cable 22. The speaker cable 22 is connected by plugging male audio plug 38 into female audio jack 28.
The arrangement shown in FIG. 1 is now common for mobile amateur radio stations. The bulkiest item is radio 10, which requires connections for both high-current voltage and an antenna. Therefore, it is desirable to locate it remotely while keeping the components with which the user interacts (microphone 14, control head 12, and speaker 16) close by. Radio manufacturers provide kits for this purpose. Each kit would typically contain a control cable 18, microphone cable 20, and speaker cable 22.
FIG. 2 shows how such a remote location kit would be used to install an amateur radio in a car 40. Radio 10 is mounted in trunk 42, where its bulk does not present a problem. Control head 12, microphone 14, and speaker 16 are mounted near the vehicle's dash in a position that is convenient for the driver. These three components are then independently connected to radio 10 using control cable 18, microphone cable 20, and speaker cable 22.
Since the three cables needed are proprietary items sold by each manufacturer, they are often relatively expensive. In addition, if the user changes to another type of radio, at least the microphone cable and control cable must be removed and replaced with different types. It would be preferable to provide a system for standardizing the cables used for remotely locating a radio. The present invention provides just such a solution.